CVE-2011-4503 in WL-111
Summary
by MITRE
The UPnP IGD implementation in Broadcom Linux on the Sitecom WL-111 allows remote attackers to establish arbitrary port mappings by sending a UPnP AddPortMapping action in a SOAP request to the WAN interface, related to an "external forwarding" vulnerability.
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Analysis
by VulDB Data Team • 08/08/2024
The vulnerability identified as CVE-2011-4503 represents a critical security flaw in the Universal Plug and Play Internet Gateway Device implementation found in Broadcom Linux firmware for Sitecom WL-111 wireless routers. This vulnerability resides within the UPnP IGD (Internet Gateway Device) component that enables automatic port forwarding configuration for devices on home and small office networks. The flaw specifically affects the WAN interface handling of UPnP SOAP requests, creating an avenue for unauthorized remote exploitation that directly impacts network security and device access control.
The technical implementation of this vulnerability stems from insufficient input validation and authentication mechanisms within the UPnP service running on the affected Broadcom Linux-based routers. Attackers can exploit this weakness by crafting and sending specially formatted SOAP requests containing UPnP AddPortMapping actions directly to the WAN interface of the device. This allows unauthorized parties to establish arbitrary port mappings without proper authentication, effectively bypassing the router's normal security controls. The vulnerability is classified under CWE-284, which addresses inadequate access control mechanisms, and specifically manifests as a privilege escalation issue within the UPnP service implementation.
The operational impact of this vulnerability extends beyond simple network access, creating significant security risks for organizations and individuals using affected Sitecom WL-111 devices. Remote attackers can utilize this vulnerability to redirect network traffic through the compromised router, potentially enabling them to access internal network services, establish backdoors, or perform man-in-the-middle attacks. The threat landscape for this vulnerability aligns with ATT&CK technique T1098.004, which covers "Windows Admin Shares" and similar privilege escalation methods, though in this case the attack vector targets network infrastructure rather than operating system components. The ability to create arbitrary port mappings means attackers can potentially expose internal services to the internet, modify network traffic routing, or gain persistent access to the local network through the compromised router.
Mitigation strategies for CVE-2011-4503 should prioritize immediate firmware updates from Sitecom or Broadcom if available, though this particular vulnerability dates back to 2011 and may no longer have official patches. Network administrators should disable UPnP functionality entirely on affected devices when possible, as this removes the attack surface entirely. Additional protective measures include implementing firewall rules that restrict access to the UPnP service ports, particularly on the WAN interface, and monitoring network traffic for suspicious UPnP activity. The vulnerability demonstrates the importance of secure service implementation and proper access controls in network infrastructure devices, as highlighted by the ATT&CK framework's emphasis on securing network services and preventing unauthorized configuration changes that could compromise entire network perimeters. Organizations should consider replacing affected hardware with modern devices that have proper security implementations and regular firmware update support to prevent exploitation of similar vulnerabilities in the future.